Compounded hydrocarbon lubricant



Patented June 1 5, 1943 COMPOUNDED HYDROCARBON LUBRICANT James 0. Clayton and Bruce B. Farrington,

Berkeley, Calif.,

assignors to Standard Oil Company of California, San Francisco, Calif., a corporation of Delaware No Drawing. Application June 10, 1940, Serial No. 339,663

16 Claims.

This invention rlates to a new and useful composition of matter comprising a compounded hydrocarbon oil. More particularly, it involves the provision of a lubricating oil containing metal salts of organic acids and an addition agent which inhibits undesirable effects of such compounds, as set forth hereinafter.

Metal salts of organic acids are known as compounding ingredients for lubricating oils and have been added thereto for variouspurposes. For example, aluminum oleate is disclosed as a dispersing agent for graphite in the United States patent to Burke No. 1,732,221, various soaps have been disclosed as pour point depressing agents, and the patent to Parker No. 2,001,108 is directed to metal naphthenates as stabilizing agents for lubricating oils; In its broader aspects this invention is applicable to compounded oils contaiuing metal salts vof organic acids of the above known types, as well as to oils containing novel types of salts hereinafter disclosed. The present invention, in its more specific aspects, is concerned with oils compounded with certain metal salts among which are polyvalent metal salts, such as salts of aluminum, zinc, tin, magnesium, calcium and chromium.

One important property of lubricating oils is pounding ingredients have been found, in general, to show undesirable corrosive effects on such bearing materials. However, these metal salt compounding ingredients are highly desirable or even necessary for other purposes, such as for inhibiting piston ring sticking in internal combustion engines such as Diesel engines.

Accordingly, it is an object of the invention to solve the, above difficulties by providing an improved compounded mineral oil containing metal salts of organic acids.

Another object of the invention is to inhibit corrosive effects of compounded lubricating oils containing metal salts of organic acids.

A further object of the invention is to increase the stability of lubricating oils with respect to oxidation or discoloration or gum formation.

A still further object is to improve the properties of-lubricating oils containing metal salts of organic acids by incorporating therein an ester containing a keto group preferably no more than two carbon atoms removed from a carbonyl group of said ester.

Additional objects and advantages of the invention will become apparent from the disclosure which follows.

Examples of metal salts of organic acids which may be incorporated in lubricating oils according to the principles of this invention are metal salts of higher fatty or aliphatic acids, metal salts of naphthenic acids, metal salts of oil-soluble substituted phenols, and metal salts of carboxylic acids containing an aryl substituent.

Among the metal salts of higher fatty acids may be mentioned: aluminum laurate, aluminum oleate, aluminum stearate, aluminum ricinoleate; zinc laurate, zinc oleate, zinc stearate, zinc ricinoleate; tin laurate, tin oleate, tin stearate, tin ricinoleate; magnesium laurate, magnesium oleate, magnesium stearate, magnesium. recin oleate; calcium laurate, calcium oleate, calcium stearate, calcium ricinoleate; chromium laurate, chromium oleate, chromium stearate, and chromium ricinoleate.

Examples of metal naphthenates are: aluminum naphthenate, zinc naphthenate, magnesium naphthenate, cobalt naphthenate, cadmium naphthenate, tin naphthenate and manganese naphthenate. The naphthenic acid component of these salts may conveniently be obtained from petroleum.

Metal phenates which may be mentioned comprise metal salts of a substituted phenol of the typeformula:

substituent are: phenyl stearic acid, naphthyl stearic acid, phenyl lauric acid, alpha benzal stearic acid, alpha benzal lauric acid, and analogous homologues of these acids formed by condensation of an aromatic aldehyde with a fatty acid according to the reaction:

m-Cm-coonun-cn m-c-coorumor") cum where R; is an alkyl and R2 an aryl radical. Aluminum, zinc, tin, magnesium, calcium and chromium as well as other polyvalent metal salts of each of the above acids may be utilized.

The invention also includes salts of polycarboxylic acids together with keto esters in hydrocarbon oils. Examples of such salts are the aluminum, zinc, tin, magnesium, calcium and chromium as well as other polyvalent metal salts of partially esterified acids of the oxalic acid series, including oxalic acid itself, malonic acid, isosuccinic or methyl malonic acid and its alkyl homologues, as well as the corresponding salts of partially esterified alkyl tartronic acid, partially esterified malic acid and its homologues, partially esterified oxyglutaric acid, partially esterified hydroxy adipic acid, partially esterified tartaric acid, partially esterifled citric acid and the like.

The second component of the composition of this invention comprises oil-soluble esters containing a keto group preferably no more than two carbon atoms removed from a carbonyl group of the esters. These types of compounds may be represented generically by the following structural formulae:

R?CHt-'fi"-ZRl I Y I In these formulae R and R1 represent an alkyl, aryl, alkaryl, aralkyl or cyclic non-benzenoid group. R and R1 may contain substituents other than the keto group, which substituents may be of either the same or a different type. X repretached directly to the molecule being substituted,

and the benzene ring contains an alkyl substituent. Examples of aralkyl radicals are radicals in which an alkyl group is attached directly to the molecule being substituted, and the alkyl group contains an aryl substituent, for instance,

keto caprylic acid; ethyl, propyl, butyl, amyl,'

hexyl, octyl, decyl, lauryl, tetradecyl, cetyl and octadecyl esters of alpha keto capric acid; ethyl, propyl, butyl, amyl, hexyl, octyl, decyl, lauryl, tetradecyl, cetyl and octadecyl esters of alpha keto lauric acid; ethyl, propyl, butyl, amyl, hexyl, octyl, decyl, lauryl, tetradecyl, cetyl and octa- .decyl esters of alpha keto myristic acid; ethyl,

propyl, butyl, amyl, hexyl, octyl, decyl, lauryl, tetradecyl, cetyl and octadecyl esters of alpha keto palmitic acid; ethyl,'propyl, butyl, amyl, hexyl, octyl, decyl, lauryl, tetradecyl, cetyl and octadecyl esters of alpha keto stearic acid.

Examples of beta keto esters are beta keto butyric acid butyl ester, beta keto butyric acid amyl ester, beta keto butyric acid hexyl ester, beta keto butyric acid octyl ester, beta keto butyric acid decyl ester, beta keto butyric acid lauryl ester, beta keto butyric acid tetradecyl ester, beta keto butyric acid cetyl ester, and beta keto butyric acid octadecyl ester.

The keto esters of this invention may be prepared by methods known in the art. The esters may be produced by esterification of the alpha keto acids, by esterification of the alpha or beta keto alcohols, or by introducing a keto group into an ester in an alpha or beta position. The beta keto acids are unstable in the free state but the esters ,of these compounds are quite stable. Consequently, beta keto esters will usually not be obtained by esterification of a free beta keto acid.

It will be understood from the foregoing discussion that the invention embraces the addition of both a metal salt of an organic acid and a keto ester as addition agents for liquid lubricating oils. Each and every one of the foregoing metal salts of organic acids may be utilized in hydrocarbon oils with each and every one of the foregoing keto substituted esters to impart improved properties to the oil; e. g. lubricating oils containing any one or more of the metal salts of fatty acids with any one or more of the alpha or beta keto esters will be found useful. Likewise, oil containing any one or more of the metal naphthenates in combination with any one or more of the alpha or beta keto esters possess advantageous properties. The same is true of combinations of any one or more of the metal salts of the phenols or of the metal salts of the aryl substitued or polycarboxylic acids with any one or more of the keto esters.

The combinations disclosed herein cooperate to give new results in hydrocarbon lubricating oils. In general, the alpha or beta keto esters reduce the corrosive effects of hydrocarbon lubricating oils on modern bearing metals, such as copperlead or cadmium-silver alloys. Such esters will reduce corrosiveness of oils containing metal salts of organic acids as much as 50% or more. Various of the metal salts of organic acids and keto esters apparently cooperate to enhance the stability of the oil against discoloration, gum formation, piston ring sticking and the like.

The proportions of addition agents utilized will depend upon the particular compounds incorporated in the oil, upon the base oil being compounded. as well as upon the conditions which the oil is to encounter during use and the properties desired. In general, from 0.1% to of the metal salts of organic acids are utilized, and more usually 0.5% to 2% thereof are found desirable. Measurable improvements in the properties of the compounded oil are obtained with as little as 0.1% of the keto ester, but as much as 1% is preferred. More than is regarded as unnecessary.

The chemical mechanism by which the results of this invention are obtained has not been established. Metal salts of organic acids appear generally to catalyze corrosive effects in hydrocarbon lubricating oils. The keto esters inhibit or offset this catalytic action. The present invention, in its broader aspects, is applicable to oils, such as highly refined or highly paraflinic mineral oils, which are in themselves corrosive to bearing metals in the absence of added metal salts of organic acids; i. e., the alpha or beta keto esters may, according to the broader principles of the invention, be utilized to inhibit the corrosive action of hydrocarbon lubricating oils on copperlead and cadmium-silver bearing metals whether or not the oils contain metal salts. However, the invention appears to find its greatest utility in oils containing metal salts of organic acids in that these salts cooperate with the esters to yield properties which are not obtainable with either type of component alone.

It is apparent that the particular ester and the particular metal salt must be selected with various factors in mind, such as the service to be encountered and the type of bearings or other machine elements to be lubricated, if the maximum benefits of the invention are to'be obtained. In general, salts containing at least ten carbon atoms are preferred. Esters containing more than ten carbon atoms are useful for imparting other properties to the oil, e. g., reducing Wear or reducing friction. While specific examples and methods of preparation of the compositions of the invention have been described, this has been done by way of illustration only and with the intention that no limitation should be imposed upon the invention thereby. Numerous modifications and variations of the illustrative examples may be effected in the practice of the invention which is of the scope of the claims appended hereto.

We claim:

1. A compounded hydrocarbon oil containing a metal salt of an organic acid in an amount sufficient substantially toincrease the corrosivity of said oil, and a corrosion inhibitor comprising an ester having a keto group no more than two car bon atoms from a carbonyl group of said ester.

2. A compounded hydrocarbon oil containing a metal salt of a higher aliphatic acid in an amount sufiicient substantially to increase the corrosivity of said oil, and a corrosion inhibitor comprising an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester.

3. A compounded hydrocarbon oil containing a metal salt of a carboxylic acid having an aryl substituent in an amount sufiicient substantially to increase the corrosivity of said oil, and a corrosion inhibitor comprising an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester.

4. A compounded hydrocarbon oil containing a metal salt of a high molecular weight phenol in an amount sufficient substantially to increase the corrosivity of said oil, and a corrosion inhibitor comprising an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester.

5. A compounded hydrocarbon oil containing a small amount of a metal salt of an organic acid suflicient substantially to increase the corrosivity of the oil, and from approximately 0.1% to 10% of an ester having a keto group no morethan two carbon atoms from a carbonyl group of said ester.

6. A compounded hydrocarbon oil containing a small amount of a metal salt of a higher aliphatic acid sufiicient substantiallyto increase the corrosivity of the oil, and from approximately 0.1% to 10% of an ester having a keto group no more than two carbon atoms from-a carbonyl group of said ester. 7. A compounded hydrocarbon oil containing a small amount of a metal salt of a carboxylic acid in an amount suflicient substantially to increase the corrosivity of said oil, and from approximately.

0.1% to 10% of an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester.

8. A compounded hydrocarbon oil containing a small amount of a metal salt of a high molecular weight phenol suificient substantially to increase the corrosivity of said oil, and from approximately 0.1% to 10% of an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester.

' 9. In a method of lubricating bearing surfaces which comprises maintaining between the bearing surfaces, one of which is a bearing metal of the type represented by cadmium-silver and copperlead alloys, a film of a lubricating oil which initially produces an eifective lubricating action but which would normally tend to corrode said hearing metal, the step of inhibiting the corrosive action of the oil on said bearing by incorporating therein from approximately 0.1% to 10% of an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester.

10. In a method of lubricating bearing surfaces which comprises maintaining between the bearing surfaces, one of which is a bearing metal of the type represented by cadmium-silver and copper-lead alloys, a film of a compounded lubricating oil containing a 'metal salt of an organic acid in an amount which would normally increase the corrosivity of said oil to said bearing metal, the step of inhibiting the corrosive action of the oil on said bearing by incorporating therein from approximately 0.1% to 10% of an ester having a keto group no more than two carbon atoms from a carbonyl group of said ester. I

11. A compounded lubricant comprising a hydrocarbon oil containing from approximately 0.1% to 5% of a metal salt of an organic acid, and from approximately 0.1% to 10% of a corrosion inhibitor comprising an ester containing a keto in which R and R1 are radicals of hydrocarbon structure; and X, Y and Z are selected from the group consistingof oxygen and sulfur.

13. An improved lubricant comprising a hydrocarbon oil containing from approximately 0.1%

to 10% of an additive of a type formula selected from the group consisting of:

n-c-z-cmcai and n-c-cra-o-z-ai in which R and R1 are radicals of hydrocarbon structure; and X, Y and Z are selected from the group consisting of oxygen and sulfur.

14. A compounded lubricant comprising a major proportion of hydrocarbon oil with the properties of said composition affecting its use as a lubricant improved by incorporating therein at least 0.1% of a metal salt of an organic acid and from approximately 0.1% to 10% of an ester containing the following characterizing group in which R and R1 are radicals of hydrocarbon structure; and X, Y and Z are selected from the group consisting of oxygen and sulfur.

15. A compounded lubricant comprising a major proportion of hydrocarbon oil with the properties of said composition affecting its use as a lubricant improved by incorporating therein at least 0.1% of a metal salt of an organic acid and from approximately 0.1% to 10% of an ester con-- taining a characterizing group of a type formula selected from the class consisting of-- JAMES O. CLAYTON. BRUCE B. FARRINGTON. 

